Dean May wrote: > Actually, no, I am referring to freon type regular a/c units. What I am > saying seems counter intuitive which is why I posted the warning. > > How does moisture condense out of the air? It is the dew point principle. > You may have heard the evening weather man talk about the dew point > temperature. For example, the current outdoor temperature may be 90 degrees > F with a RH of 60%, the dew point temperature would be 74 degrees. What that > means is, assuming barometric pressure remains constant, if the temperature > would cool to 74 degrees the RH would approach 100% and water would begin to > condense out of the air. This is exactly how dew forms on the grass > overnight. http://en.wikipedia.org/wiki/Dew_point_temperature Right. > This is also how the a/c units pull moisture out of the air. As the air goes > over the evaporator coils the temperature drops below the dew point (which > means RH goes to 100%). For every degree below the dew point the air is > cooled, water must condense out. So for our example of dew point at 74 > degrees, the air coming off the coils may be around 40 degrees F. Air at 40 > degrees and 100% RH won't hold as much water as air at 74 degrees and 100% > RH. The difference is the amount of water that is condensed out. Right again. > What is important to realize, though, is the RH of the air coming off the > coils is still at or near 100%. This is the air that comes out of the vents, > and if it is blowing on the piano, you are blowing really moist air on it > (cold, but moist) and the piano will pick up moisture accordingly. Wrong. How can air that has had moisture removed from it by the process you outlined above have more moisture than the ambient room air from which it came? Again, RH% isn't MC. Ron N
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